1. Field of the Invention
The present invention relates a capacitive touch panel, and more particularly, to an electrode pattern design of a capacitive touch panel.
2. Description of the Prior Art
In flexible displays or other wearable devices, it is difficult to make reference grounds corresponding to capacitive sensing electrodes of the display be the same, causing the capacitances of the sensing electrodes easy to be influenced by environment factors. In addition, to solve the manufacturing cost, a touch panel and a liquid crystal module (LCM) are joined together by using edge lamination (also known as air gap or air bonding) technique. However, using the edge lamination to combine the touch panel and the LCM make an air gap between the touch panel and the LCM, and when a touch is applied on the touch panel, a defection of the touch panel will cause non-uniform distribution of the capacitances in the touch panel, and the sensing signals will be influenced.
Please refer to FIG. 1, FIG. 2 and FIG. 3 together, FIG. 1 is a diagram illustrating an active array of a touch panel 100, FIG. 2 shows a cross-section view of the touch panel 100 and a LCM 210 and the capacitors existed in the touch panel 100 and the LCM 210, FIG. 3 shows the cross-section view of the touch panel 100 and the LCM 210 when a touch is applied on the touch panel 100 and the capacitance variation of the capacitors existed in the touch panel 100 and the LCM 210. As shown in FIG. 1, the active array includes a plurality of first electrodes TX1-TX4 and a plurality of second electrodes RX1-RX4, where the first electrodes TX1-TX4 are used to receive scan signals, and the second electrodes 120_1-120_4 are connected to a detecting circuit (not shown), where the detecting circuit detects changes of voltages of the second electrodes RX1-RX4 to obtain capacitance variation information to determine a position of the touch.
FIG. 2 shows the capacitors CTX, CRX and CM existed in the touch panel 100 and the LCM 210, where CTX is the capacitor between each first electrode TX1-TX4 and a thin film transistor (TFT) array 212 of the LCM 210, CRX is the capacitor between each second electrode RX1-RX4 and the TFT array 212, and CM is the mutual capacitor between each first electrode TX1-TX4 and its neighboring second electrode RX1-RX4. It is note that the capacitors CTX, CRX and CM shown in FIG. 2 and FIG. 3 are parasitic capacitors rather than intentionally placed capacitors. As shown in FIG. 2, the capacitors CTX and CRX have low capacitances, and the capacitors CM have relatively large capacitances, that is most of the electrical charges are stored in the capacitors CM.
In FIG. 3, when a touch is applied on the touch panel 100, the touch panel 100 is distorted and the air gap is reduced. At this time the capacitances of some capacitors are changed (e.g. CRX′, CTX′ and CM′ shown in FIG. 3), in detail, the electrical charges are transferred to the capacitors CTX and CRX, that is the capacitances of the capacitors CTX and CRX are increased, the capacitances of the capacitors CM are decreased. Therefore, because the capacitances of the capacitors CM are abnormally changed, the voltages detected by the detecting circuit may be influenced, causing detecting errors.